Development of an integrated modeling framework for ... · deformable porous pulp media during the...
Transcript of Development of an integrated modeling framework for ... · deformable porous pulp media during the...
We have performed high-resolution direct numerical
simulation of microscale flows in both synthetic
representations of felt and geometries obtained from 3D
tomography of industrial felts. Preliminary data shows that• Pressure drop in felt is nonlinear and thus constant permeability
assumption does not hold for continuum models;
• Fully resolved simulation of single phase flow in uncompressed
and compressed pore scale geometries obtained from image
data is useful in obtaining permeability to porosity relationships
that can be used to parameter fit continuum models;
• Diffusive front tracking of two phases has been demonstrated
and can be extended to track sharp interfaces between multiple
fluids and triple point contact angles.
Development of an integrated modeling framework for simulating
water removal at the press section in paper making
Project objective
Yue Hao (LLNL), David Trebotich (LBNL), Wei Wang (LLNL),Jun Xu and David Turpin (Agenda 2020)
Lawrence Livermore National Laboratory / Lawrence Berkeley National Laboratory / Agenda 2020
Technical approach
Summary
Integrated modeling framework for
dewatering/rewet simulation
Direct simulation of pore-scale
flow in porous paper/felts• Maximizing water removal can significantly reduce the energy-
intensive drying process in paper-making.
• After pressing water from the paper pulp, re-wetting is occurring.
• Paper de-watering and re-wet phenomena are not currently well
understood primarily due to lack of sufficient data and reliable
models
Paper machine press section Close-up view of press nip
A B
Paper
Roll
Roll
Felt
Illustration of press nip
• The objectives of this project are to
– Leverage the HPC capabilities at LLNL and LBNL to
develop an integrated, multi-physics modeling framework
as a critical first step to understanding and reducing rewet
at the press section.
– Provide the pulp and paper manufacturing industry with
insights to inform the designs of more energy efficient
processes and equipment, resulting in energy reduction.
We leverage advanced simulation capabilities, experimental
measurements and paper machine data to develop an integrated,
multi-physics modeling framework.
• LLNL develops a continuum simulation framework to couple mechanical
and two-phase flow models
– Use Richards’ equation to describe two-phase flow in paper/felts
– Employ modified Cam-Clay model to describe paper plastic
deformation
• LBNL develops pore-scale flow modeling capabilities
– Perform high-resolution direct simulation of microscale flow
in complex pore structures in paper pulp and press felts
– Use pore-scale flow modeling to inform better parametrization of
porosity and permeability for continuum-scale computations
• Agenda 2020 provides the domain expertise and data to support model
calibration, validation, and application
Continuum modeling of coupled water
flow and deformation processes
• We have developed an integrated multi-physics modeling
framework for simulating two-phase (water and air) flow in
deformable porous pulp media during the wet pressing
process in paper making.
• We will work with paper industry to apply the developed
model to help guide press section configuration and roll/felt
design to minimize rewet.
integrated flow and
mechanical modeling
pore-scale flow model
paper machine
press data
paper/felt
CT and SEM data pore-scale deformation
laboratory
measurements
sheet
felt
continuum-scale flow
and mechanical model
paper
felt
UQ and sensitivity analysis
The model is able to fit the measured machine data, and predict
that pressing increases the web dryness from 20-35% to 30-50%.
1
shoe press nip configuration paper dryness evolution
felt
paper
312 mm
initial felt thickness = 3.5 mm
shoe press pressure
deformation and dryness of compressed paper/felt
paper thickness = 400 μm
water saturation distribution in compressed paper/felt
porosity distribution in compressed paper/felt
Model calibration spans scale, configuration and uncertainty
Non-linear pressure drop
Slice from felt CT image
3D pore-scale felt model using
geometry reconstructed from image
data (pressure shown) permeability k =
7.732x10-11 m2 Computed on 6912 cores
pore-scale flow in
uncompressed felt
K1/K2 = (ϕ1/ ϕ2)n
n ~ 5.0for continuum model
pore-scale flow in
compressed felt
computed bulk
porosity/permeability are
used to describe porosity-
permeability relationships.
two-phase flow simulation of diffusive and advective water movement in a synthetic felt
time = 0.12 time = 0.20
sensitivity analysis of paper dryness curves
made on one thousand realizationspaper dryness evolution at a roll press section
Joshua White, and Michael Homel (LLNL), and David Lange, David McDonald, and Stefan Probst–Schendzielorz (Agenda 2020)
This research was supported by the High-Performance Computing for Manufacturing Project Program (HPC4Mfg), managed by the U.S. Department of Energy Advanced Manufacturing Office within the Energy
Efficiency and Renewable Energy Office. It was performed under the auspices of the US Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344. LLNL-POST-725122